Thermoresponsive device



Aug. 31 1926.

G. A. BURNHAM THERMORESPONSIVE DEVICE 2 Sheets-Sheet 1 /4 f y Z Filed April 12. 1922 Aug. 31 1926.

G. A. BURNHAM THERMQRESPONSIVE DEVICE Filed April 12. 1922 2 Sheets-Sheet 2 Ill-5...:

Patented Aug. 31', 1926.-

UNITED STATES PATENT- OFFICE.

eaoaen a. sum. sauce iussscr'mssr'rs, assionoa, BY um ASSIGN- mmraoi-Unme oonroaarron, or nosron,

a conronarros or mssacnusnr'ra monasrossrva DEVilOl.

Application fled April in, 1922. Serial Io. mp2s.

. This invention relates to thermally-controlled .electric circuit controllers and has particular reference to a circuit controller including a thermal] responsive element 5 adapted to be heated y the current carried in an electric circuit to control a circuit.

The usual t of thermal] controlled circuit contro er is usually cult to adjust to operate on various values of current; 1 for instance, a circuit controller which may operatesatisfactorily when influenced by a current of say five amperes, can not be adjusted readily to work satisfactorily for say a current of two amperes, or ten amperes. An object of this invention is the provision of a thermall controlled circuit controller which can o adjusted for different values of current within a relatively wide 0 ran may include a thermally enced member adapted to control a circuit and a heating device, actuated by current flowing throng it and arranged in heat imparting relation 25 with said thermally influenced member. Said heating member may be adjustable for variousvalues of current whereby opera: tively to affect the thermal member for any selected value of current within its range. 80 Fig. 1,is a side view of'athermal circuit controller embodying the invention.

Fig. 2 is a plan view of the controller of Fig. 1 withthe cover removed;

Fig. 3 is a transverse section along line- 86 3-3 of Fig. 1.

Fig. 4.- is a lo 'tudinal sectional elevation of the contro lfia r of 1.

Fig.1 5 is a diagrammatic illustration of the controller connected, for the protection 40 of amotor.

Fig. 6 iii a side elevation, partially in sec tion. of a modified form of controller.

Fig. 7 is a detail of a further modified form of controller. I Fig. 8 is a lo 'tudinal' sectional. 1cm- 1 tion of a Qdifi form of control] r arin a tubular enclosing Fig. 9 is an end viewof the controller of l0 10 is a section along line '10+10 of ig. 11 is a plan view of the controller of Fig.12isasectionaliriewsimilartoFig.

e structure embodyfi the invention- 8 but withthe thermal circuit-closing position.

As here shown, rated in the structure including the supporting member or base 10 hav' the abutment 11 rising thereabove. Pre erably the base and abutment are made of some insulating material as porcelain. The heating element for'thc thermal elenientmay prise the two carbon or equivalent blocks 12 and 13 adapted to be supported on the base 10. Said relatively by engagement with the abutment -11 of the base. The other carbon block 13 is adapted to be relatively'movable, and is slidable on the base and is adapted'to be pressed, with a variable pressure, against the stationary carbon block by suitable means as, for instance, the spring 14 carried by the end of the adjusting screw 15, which latter is threaded into a ledge 16 carriedby the base '10. A cover -17 may removably enclose the elements of the controller, and said adjusting screw may extend'outwardly beyond said cover and terminate in a knob 18. R0- tation of said screw in one compress the spring 14 and thereby increases the contact pressure between said carbon blocks, andithe value of current at which the thermal element will operate; and rotation in the opposite direction recarbon block 12 is adapted 'to be duces the contact pressure, and the current.

setting of the controller. A calibration member 19 may be carried by a stationary part of the device. and bear calibration indications, 'as amperes, adapted to register with a part of the knob, value of current at which to 0 rate.

T e thermal element 20 may comprise a element normally oomstationary and is held in positiontoindicate the the device is set 1,591,11gil the invention is incorpo- Y direction acts to strip of thermostatic metal comprising two metals ha dissimilar ex cients seen together.- Sai ment 20 is carried by and is in heat-receiving relationship with one of the carbon blocks, and preferably the stationa carbon block 12, as by ha one and t ereof imbedded in said block, and the other end thereof is extended outwardly from said block and bears a contact 22. Said thermal element is adapted to receive heat from the ansion coeflithermal elecarbon block and expand and flex its outer' and away from a, preferably and toward and said post 24 mg post 29.

v Said movable carbon block 13 may be connected, by meansof the flexible conductor 30, to the binding post 31.

.When the device above described is employed for theprotection of an electric motor, for instance, I prefer to utilize the thermal element merely to control a control circuit carrying but a small value of current, and to influence the thermal element from the motor circuit by current passed through the heating elements. Accordingly, in Fig. 5, the thermal element 20 is shown in the control circuit including the trip coil 36 of the circuit breaker 37 which latter is in control of the motor'38. The carbon blocks- 12 and 13 are placed in the motor circuit 39. When an undue amount of heat is generated in the carbon blocks, as by reason of an overload in the motor circuit, the thermal element is expanded to close the control-circuit 35 and open the circuit breaker 37.

The carbon blocks 12 and 13 here comprise the heating elements for the thermal element. The electrical contact at the junction between the blocks is imperfact and current passing through the junction generates heat at the junctign which is transmitted through the stationary carbon block to the thermal element and heats said element. When a normal value of current passes through the blocks the heat generated is adapted to be insuificient to effect the opera-. tion of the thermal element, When, however, an abnormal amount of current'flows through said carbon blocks, the resultin increased heating efiect expands the therma element to effect the control of its. circuit.

Said carbon blocks provide means to vary the current value at which the thermal element 20 is effectively operated. By increasmg the pressure between said blocks the contact area at thejunction is increased and the resistance of the junction is reduced and consequently the amount of heat necessary to operate the thermal element will not be generated until the current passing through the carbon blocks is increased. Consequent- 1y, by varyin the pressure between the car- .bon. blocks, t e current value at which the thermal element will operate, is varied.

In Fig. 6, the thermal element comprises a tube 4.0 filled with an .expansible', electrically conducting, fluid, as mercury. Said tube is received in a recess in the stationary block 12 and the expansible fluid is adapted adapted to to expand under heat generated at the junction of said blocks and bridge and electrically connectthe contact members 41 and complete the control circuits.

In Fig. 7 the carbon blocks 12 and 13 are adapted to be held in engagement at a uniform and invariable pressure by means of the springs 14 but said block 13 is be moved to present a variable area of engagement with said stationary block, whereb to vary the value of current at which the evice will operate.

Fig. 8 illustrates a modification of the invention adapting it for use to replace enclosed fuses and to be received in the usual form of use clips.

The tubular enclosing casing 50 of insulating material comprises the sup orting member for the device and has t e externally screw-threaded end-portions 51 on which the end-caps 52 and 53 are removably screwthreaded. Said end caps are adapted to form the terminals for the motor, or similar,

circuit and are adapted to be received removably in the spring fuse clip 54. A third terminal for the controlling circuitincluding the thermal element comprises the ring 55 disposed on the tubular casing intermediate and insulated from the end caps 52 and 53. A stationar carbon block 56 is received within the tubu ar casing .50 and is adapted to bear against and make electrical contact with the end cap 52. It may be held in position against rotation by the set screw 57 which may be carried by the casing 50 and enter a recess 58in said block. A thermal element 59, which may be similar to the thermal element 20 of Fig. 1, is imbedded in said block 56 in heat conducting relationship therewith. Saidthermal element is extended substantially axially within the enclosing casing 50 and bears a contact 60 at its free end which is adapted to be moved into and away. from electrical engagement with an adjustable contact 61 carried by'the ring 55, by the flexing of said thermal elementdue to the heating thereof, to control the control circuit including said thermal element. A movable carbon block 62 is disposed within said enclosing casing 50 to bear against the stationary block 56; and said movable block may have the passage 63 therein in which the thermal element 59 and the stationary contact 61 are received; and the dimensions of said passage are such that the carbon block is free from'electrical contact with the thermal element and stationary contact. Said movable carbon block may berestrained from rotation while in.

contact with the stationary block 56 by any mag bot and the thermal element .pand and engage the stationary contact 61 the ler including and the pressure maybe adjusted b' the screw 67 which-is ad ustably thread axially in the end cap 53 and bears against said spring member, Said screw 67 may have a knob icon-u of tha casing, by which 'te screw may be rotated, and a pointer 69 carried thereby may register with indicia 70 on the end wall of the end cap 53 to indicate the current value at which the device is set to operate.

The device illustrated in F ig, 8 is adapted to control a normally opencontrol circuit is adapted to, ex-

to close the controlling circuit, a

In the modification illustrated in Fig, 12, device is arranged to control a-normally cl control circuit and the thermal element 59' is arranged normally to engage the stationary contact 61' and maintain the controlling circuit closed. With an excess amount of current passing through the. car-' bon blocks, with consequentexcess heating, the element is arranged to flex and interrupt the control circuit.

The heating element for the thermal element is designed only incidentally to vary the gurrent in the circuit including said elemen The heating elements'may be other than contacting carbon blocks and the structure may be otherwise modified without departfrom the spirit of the invention.-

claim: v 1. A thermallv responsive circuit controlan electrical heating resistance, a thermally-responsive, circuit-controlling element influenced by the heating of said re-' sistance to operate to control its circuit, and means to govern the circuit-controlling operation of said element including means to vary the heating 'efl'ect of said resistance on sai element; 2. A thermally responsive circuit controller including an electrical heating resistance, a thermal] responsive, circuitcontrollin element uenced by the heating of sai resistance to operate to control its circuit, and meansto vern the circuit-controlling operation of said element including means to vary the electrical conductivity of said reler including a to vary said electrical heating deviceto the, pasage ce. e 3. I A thermalldy responsive circuit controla single electrical heating device for said elgment, and means to vary .the heat' effect of said heat' device upon said ermally-res nsive ement comprising means e eflective cross-sectional area of of an electric circuit. s

4. A thermally responsive circuit controller comprising a thermally nsive element adapted to control a circu t, and. heat determined values of ment a trical contact and ermally responsive element,

comprising two ing means adapted to be influenced by an to heat said thermally -re-. sponsive element, said heating electric circuit means mclud mg two co-ac'ting members having a variable resistance contact between them withipressure-means to vary'the contact resistance;

5. A thermally responsive circuit controller comprising a thermally responsive element adapted, to control a circuit, and an adjustable electrical contact resistance arranged in heat influencing relation with said element including tact resistance while maintaining the circuit through it, whereby to effect the operation of said thermally responsive element at prethrou h said resistance. 6. thermally responsive circuit controller com rising a thermally nsive ele;

diipted to control a circuit, and electrical heating means for said'element'comprising two heating blocks disposed in electrical contact and in heat influenc' relacurrent flowing means to" adjust said con- I tion with said thermally res nsive e ement in series by an and arranged to be traverse become heated electricfiurrent, whereby to at their point ofcontact;

7. A thermally responsive circuit controller comprising a thermally responsive element adapted to control a circuit, and electrical heating means for said element col:- prising two heatin blocks in e tricalcontact and heat in none relation with said thermally responsive ement and arranged to be traversed in series by an electric current, and means to vary the contact pressure between said blocks v 8. A thermally responsive circuit control- .ler com rising a thermally responsive element a apted to control a circuit, and electrical heating means for said element com prising two heating blocks d' U in elecin heat uenci tion with said thermally responsive ifiement and arranged to'be traversed in series by an electric current, and means to vary the area of contact between said blocks.

rela- 1 v9. A thermally responsive circuit controller, comprising a thermally responsive element adapted to control a circuit and,

means for said element comprising two eating blocks dis in electrical contact and arranged to traversed in series by an electric circuit and adapted to be heated due to the contact resistance therebetween, said thermally responsive element arranged in heat receivi electrical heatin relation with one of said blocks.

nsive circuit con- 10. A thermally ermally responsive troller comprising a t ersedin series by an electric circuit and III element adapted to control a circuit and;

eating-blocks dispgsed in travadapted to be heated due to the contact re-, sistance therebetween, said thermally responsive element arranged in heat receiving relation with one of said blocks and means a to heat said block including a second carblock, and means to pass an 's'aid blocks, and means bon block in electrical contact'with said first electric current between said blocks including circuit terminals electrically connected with said books.

12. A thermally responsive circuit controller comprising a carbon block, a thermally responsive element arranged in heatreceiving relation with said block, and means to heat said block including a second carbon block in electrical contact with said first block, means to pass an electric current between said blocks including circuit terminals electrically connected with said blocks, means to vs the effective area of contact between said locks.

13. A thermally responsive circuit controller comprising a carbon block, a thermally responsive element arranged in heatreceiving relation with said block, and means to heat said block including a second carbon block in electrical contact with said first block, means to pass an electr c current between said blocks including oncuit terminals electrically connected with to vary the contact pressure between said blocks.

14. A thermally res onsive circuit controller comprising a car n block, a thermal-' ly responsive element imbedded in said block, and means to heat said block including a second carbon block in electrical contact with said first block, and means tric current through said blocks in series including circuit terminals electrically con nected with said blocks.

15. A thermally res onsive circuit controller comprising a car 11 block, a thermally responsive element imbedded in said block, and means to heat said block including a second carbon block in electrical contact with said first block, means to pass an electric current through said blocks inbe cluding circuit terminals electrically connected with said blocks and means to vary the effective area of contact. between said blocks.

Q16. A thermally esponsive circuit controller comprising a supporting member having an abutment, .a relative 3 My carbon block carried .by sai supporting member against said abutment, a thermally responsive element carried b and in heat receiving relation with sai carbon to vary the contact pressure between said first block, a

and.

to pass an elec- 'gagement with said other end cap,

caps removably carried by the ends of stationblock, a stationary contact member disposed in o erative relation with said element, a relatively movable carbon block carried by said supportin member in contact with said means to include said blocks in series in an electriccircuit. 17 A thermally responsive circuit controller com rising a supporting member having an a utment, a relatively stationary carbon block carried by said su porting member against said abutment, a t ermally responsive element carried by and in heatreceiving relation with said carbon block, a stationary contact member disposed in operative relation with said element, a relatively movable carbon block carried by said I ing, a relatively stationary carbon block disposed within said casing and in electrical engagement with one of said end caps, a thermally responsive element carried by said block within said casing, a relatively movable carbon block disposed within said casing and in contact with said relatively stationary carbon block and in electrical engagement with said other end cap, and a conducting ring carried externally intermediate the ends of said casing having a contact arranged in operative relation with said thermally responsive member.

19. A thermally responsive circuit controller com rising a tubular enclosing casing of insu ating material, metallic endcaps removably carried by the ends of said casing, a relatively stationary carbon block disposed within said casing and in electrical engagement with one of said end caps, a thermally responsive element carried by said block within said casing, a relatively movable carbon block disposed within said casing and in contact with said relatively stationary carbon block and in electrical enand a contact carried by said casing intermediate the ends thereof arrange in operative relation with said thermally responsive mem- 20. A thermally responsive circuit controller comprising a tubular enclosing casingof insulating material, metallic ens sai casing, a relatively stationary carbon block disposed within said casin' cal engagement with one 0 said end caps. 'a thermall responsive element carried by said bloc and within said casing, a relative ly movable carbon block disposed within said casing and in contact with said relaand in electrimember, and means to adjust the contact pressure between said carbon blocks.

21. A thermally responsive circuit controller comprising a tubular enclosing casing of insulating material, metallic end caps removably carried by the ends of said casing, a relatively stationary carbon block disposed within sald casing and in electrical engagement with one of sand end caps, a

thermally responsive element carried by said block within said casing, a relatively movable carbon block disposed within said casing and in contact with said relatively stationary carbon block andin electrical engagement with said other end'cap, a contact carried by said casing intermediate the ends thereof arranged in operative relation with said thermally responsive member, and means to adjust the contact pressure between said carbon blocks, comprising an adjusting screw threaded in one of said end caps and arranged to exert a pressure on said relatively movable carbon block.

22. A thermally responsive circuit controller comprising a tubular enclosing casing of insulating material, metallic end caps removably carried by the ends of said casing, a relatively stationary carbon block disposed within said casing and in electrical engagement with oneof-said end ca s, a thermally responsive element carried by said block within said casing, a relatively movable carbon block disposed within said casing and in contact with said relatively stationary carbon block and in electrical engagement with-said other end cap, a contact carried by said casing intermediate the ends thereof arranged in operative relation with said thermally responsive member, and

means to adjust the contact pressure between" said carbon blocks comprising an adjusting screw threaded in one of said end caps and arranged to exert a pressure on said relatively movable carbon block and a spring member disposed within the casing and interposed between said adjusting screw and relatively movable carbon block.

23. A thermally responsive electric circuit controller comprising a tubular enclosing' casing, a thermally-responsive circuitcontr'olling element disposed within said casing having electrical heating means for it, and adjusting means independent of the circuit through said heating means and disposed externally of the casing arranged to adjust the heating efi'ect of said heating means on said circuit'controlling element.

24. A thermal relay including the combination of a pair of contacting members having a resistancecontact-junction which is adapted to be heated due to the passage of an electric current through the contact junction, and a thermal device responsive to such heating.

25. A thermal relay including thecombination of a pair of contacting members having a resistance contact-junction which is adapted to be heated due to the passage of an electric current through the contact junction, and an electric circuit controller having means responsive to such heating.

26. A thermal relay including the combination of a pair of contacting members having a resistance contact-junction which is adapted to be heateddue to the passage of an electric current through the contact unction, means to vary the resistance of the contact junction and a thermal device responsive to such heating;

In testimony whereof, I have signed my name to this specification.

GEORGE A. BURNHAM. 

